Strawberry plant named `Laguna`

ABSTRACT

`Laguna` is a short-day (June-bearing) cultivar similar to `Chandler` (U.S. Plant Pat. No. 5,262) with similar total productivity and somewhat later productivity, large and very symmetrically conic fruit, firmer fruit, and a larger and more vigorous plant.

DESCRIPTION

This invention relates to a new and distinctive short-day type cultivar designated as `Laguna`, which resulted from a cross performed in 1988 between the cultivar `Irvine` (U.S. Plant Pat. No. 7,172) and advanced selection Cal 85.92-602.

`Laguna` was first fruited at the University of California South Coast Research and Extension Center, near Irvine, Calif., in 1989, where it was selected, originally designated Cal 88.66-616, and propagated asexually by runners. Asexual propagules from this original source have been tested at the South Coast Research and Extension Center, the Watsonville Strawberry Research Facility, and to a limited extent in grower fields starting in 1990.

FIG. 1 shows the general flowering and fruiting characteristics of the plant;

FIG. 2 shows a typical mature leaf during late spring; and

FIG. 3 shows representative midseason fruit.

`Laguna` is typical of short-day types and produces fruit over an extended period when treated appropriately in arid, subtropical climates. `Laguna` differs from `Irvine` in that `Irvine` is a day-neutral type with essentially no photoperiodic flowering response and is very difficult to grow as compared to `Laguna.` The production pattern for `Laguna` is similar to that for `Chandler` (U.S. Plant Pat. No. 5,262); it produces equivalent quantities of early-season fruit, and persists somewhat later in the season in cool mediterranean climates. `Laguna` will be of special interest for winter plantings, where `Chandler` has been successful, and for summer plantings where `Pajaro` (U.S. Plant Pat. No. 4,538) has been successful. Because of its late season production, `Laguna` is likely to be adapted to production objectives in central California, as well as in southern California.

Plants and foliage: Fruiting plants of `Laguna` are larger, more erect, and more vigorous than plants of `Chandler`, and are generally larger and similar in form to `Oso Grande` (U.S. Plant Pat. No. 6,578). `Laguna` forms branch crowns in greater quantity than `Chandler` with similar or greater branching than `Oso Grande`. When propagated in the nursery, `Laguna` has similar or greater runner production capacity compared with `Chandler`. Comparative statistics for foliar characters, including leaf color, near mid-season are given for the three cultivars in Table 1 with visual comparisons of leaf color to the Munsell color scale (Nickerson Color Fan) given in Table 5. Leaf color is distinctly lighter on the underside for `Laguna`; the differential is larger than for `Chandler` and similar to that for `Oso Grande`. Individual leaflets for `Laguna` are larger but otherwise similar in shape to those of `Chandler`, and are more elongated than for `Oso Grande`. Leaves (including petioles) are longer and much broader than for `Chandler`. Petioles are thicker and more stiff than those of `Chandler` and are similar to those of `Oso Grande`. Paired stipules, borne in a median position on the petiole, appear as small, stalked, ovate to heart-shaped structures on some leaves for `Laguna` and on most leaves for the comparison cultivars. Stipule size varies greatly both within and among individual plants for `Laguna`, and one or both stipules are frequently absent or may abscise as the leaf matures. Leaf and petiole pubescence characters for `Laguna` are similar to those for `Oso Grande`, except that tomentum on leaves are substantially less dense. Also, leaves for `Laguna` are similar in color to leaves of `Chandler` and `Oso Grande`. Visual comparisons of fruit color according to the Munsell color scale (Nickerson Color Fan) are given in Table 5. `Laguna` has flat (occasionally concave) leaves, which are easily distinguished from `Chandler`, and which are similar in convexity to `Oso Grande`.

Isozymes in leaf extracts: `Laguna` has been classified for three isozyme systems using starch gel electrophoresis (Table 2): Phosophoglucoisomerase (PGI), Leucine Aminopeptidase (LAP), and Phosphoglucomutase (PGM). It is distinguishable from all other short-day cultivars released to date except `Oso Grande`. For electrophoretic procedures see: J. Amer. Soc. Hort. Sci. 106:684-687.

Disease and pest reaction: `Laguna` is moderately resistant to common leaf spot (Ramularia tulasnei) and powdery mildew (Sphaerotheca macularis). When treated properly, it has equal or greater tolerance to two-spotted spidermites (Tetranychus urticae) than `Chandler`. `Laguna` is tolerant to strawberry viruses encountered in California.

                  TABLE 1                                                          ______________________________________                                         Foliar characteristics for `Laguna`, `Chandler`, and `Oso Grande`.                       Cultivar                                                             Foliar Character                                                                           `Laguna`   `Chandler` `Oso Grande`                                 ______________________________________                                         Mid-tier leaflet                                                               Length (mm)                                                                    mean        95.4       82.4       77.2                                         range       82-115     78-94      75-80                                        Width (mm)                                                                     mean        83.6       71.4       67.6                                         range       70-110     63-88      62-71                                        Mid-tier leaf                                                                  Length (mm)                                                                    mean        274.4      244.2      191.6                                        range       252-315    218-262    170-200                                      Width (mm)                                                                     mean        161.4      148.0      137.2                                        range       140-185    132-158    130-149                                      Leaf color                                                                     (CIELAB)*                                                                      L*                                                                             mean        30.8       31.4       31.9                                         range       29.2-32.3  27.1-33.3  29.9-33.0                                    a*                                                                             mean        -7.1       -8.0       -5.3                                         range       -5.3--8.7  -5.2--8.2  -4.2--8.3                                    b*                                                                             mean        15.6       16.0       15.5                                         range       13.1-20.4  12.9-21.4  12.5-20.6                                    # leaflets/leaf                                                                            3          3          3                                            Leaf convexity                                                                             flat/slight                                                                               concave    concave                                                  concave                                                            Serrations                                                                     number      moderate   many       moderate                                     shape       semi-round semi-pointed                                                                              semi-round                                               semi-pointed                                                       Leaf pubescence                                                                            sparse     moderate/  moderate/                                                           sparse     heavy                                        Petiole pubescence                                                             density     heavy      heavy      heavy                                        direction   perpendicular                                                                             acropetal  perpendicular                                ______________________________________                                          *CIELAB is the abbreviation of the international color system known as         "Commission Internationale De L'Eclairage" 1978. Recommendations on            uniform color spaces -- color difference equations, psychometric color         terms, Supplement No. 2 to CIE Publication No. 15. PARIS.                

                  TABLE 2                                                          ______________________________________                                         Isozyme phenotypes for `Laguna`, `Chandler`, and `Oso Grande`.                 Cultivar                                                                       Locus   `Laguna`     `Chandler`                                                                               `Oso Grande`                                    ______________________________________                                         PGI     A2           A1        A2                                              LAP     B3           B3        B3                                              PGM     C2           C1        C2                                              ______________________________________                                    

Flowering, fruit, and production characteristics: Comparative statistics for flower and fruit characters, including fruit color, near mid-season are given for `Laguna`, `Chandler` and `Oso Grande` in Table 3. The primary flowers for `Laguna` are larger than those of `Chandler` and `Oso Grande`; the sepals for `Laguna` are substantially larger than for the comparison cultivars. Each primary flower has 6-8 petals. The calyx for `Laguna` is usually even with the shoulder of the fruit, but is occasionally slightly indented. The primary fruit shape for `Laguna` is a very symmetrical and conic, with secondary fruit usually similar in shape. External fruit color for `Laguna` is lighter and substantially more orange than fruit of `Chandler` and `Oso Grande`; internal color is lighter than for `Chandler` and `Oso Grande`. Achenes vary from yellow to light red, and are slightly indented; the fruit is glossy, but not as glossy as `Chandler`.

`Laguna` has been tested under a variety of cultural regimes, and optimal performance is obtained when nursery treatments, pre-plant chilling regimes, plant densities, and nutritional programs similar to those that optimize performance for `Chandler` are used. In general, `Laguna` is more adapted to early-season planting with less supplemental chilling than `Chandler`.

`Laguna` has similar average fruit size and yields to those of `Chandler` and `Oso Grande` (Table 4). `Laguna` is similar to `Chandler` and `Oso Grande` in its production pattern, although it produces better quality fruit late in the production season than either comparison cultivar (with conventional winter planting). Commercial appearance ratings have been better than those for `Chandler` or `Oso Grande`. Fruit firmness for `Laguna` is equal to or greater than that for `Oso Grande`, and the fruit is substantially firmer than fruit from `Chandler`. Subjectively, `Laguna` has very good flavor, somewhat less aromatic than `Chandler`, somewhat less sweet but with better acid balance than `Oso Grande`. The fruit will be outstanding for both fresh market and processing, due to its firm flesh and will be useful for home garden purposes.

                  TABLE 3                                                          ______________________________________                                         Flower and fruit characters for                                                `Laguna`, `Chandler`, and `Oso Grande`.                                                    Cultivar                                                           Character     `Laguna`  `Chandler`                                                                               `Oso Grande`                                 ______________________________________                                         # petals                                                                       mean           6.4       6.6       5.0                                         range         6-8       6-8       5-5                                          Flower position                                                                              exposed   even/     exposed                                      (relative to foliage)   exposed                                                Calyx diam. (mm)                                                               mean          52.8      47.7      34.1                                         range         45-56     45-53     27-38                                        Corolla diam. (mm)                                                             mean          41.8      39.3      32.2                                         range         38-48     36-46     27-41                                        Fruit shape                                                                    length/width   1.10      1.33      1.06                                        ratio                                                                          subjective    conic     flat conic                                                                               blocky/conic                                 Calyx position                                                                               even/slight                                                                              even/slight                                                                              even/slight                                                indent    neck      indent                                       Seed position slight    even/slight                                                                              even                                                       indent    indent                                                 Fruit color (CIELAB)                                                           external                                                                       L*            29.0      23.6      22.4                                         a*            38.2      38.5      31.2                                         b*            25.4      14.8      17.2                                         internal                                                                       L*            54.3      46.2      54.1                                         a*            27.0      39.1      30.4                                         b*            21.3      29.4      22.7                                         ______________________________________                                    

                  TABLE 4                                                          ______________________________________                                         Performance for selection `Laguna` compared with `Oso Grande`                  and `Chandler` at the South Coast Research and Extension Center                in 1991. All plants were dug from the South Coast nursery on                   October 1 and planted October 2 (68"/4-row beds, 23,061                        plants/A, 100 g/plant = 425 Crates/A).                                                  Yield    Total           Appear-                                               To 4/1   Yield    Size   ance   Firm-                                          (g/plant)                                                                               (g/plant)                                                                               (g/fruit)                                                                             Score  ness                                  ______________________________________                                         `Laguna` 473      1,510    22.7   4.4    5.0                                   `Chandler`                                                                              463      1,738    23.3   3.9    4.0                                   `Oso Grande`                                                                            530      1,675    25.0   3.8    4.9                                   ______________________________________                                    

                  TABLE 5                                                          ______________________________________                                         Munsell color classification for leaf and fruit characters.                    Munsell                  Munsell                                               Leaf Color Classes       Fruit Color Classes                                          Upper      Lower                                                        Item   (Adaxial)  (Abaxial)  External                                                                               Internal                                  ______________________________________                                         Chandler                                                                              5GY 4/3    5GY 5/6    5R 5/13 7R 5/13                                          5GY 5/6               5R 4/12                                           Oso    5GY 4/3    5GY 5/6    5R 5/13 7.5R 7/9                                         5GY 3/2    7.5GY 6/8  7.5R 5/13                                                                              7.5R 6/12                                 Laguna 7.5GY 6/8  5G 6/8     7.5R 5/13                                                                              2.5R 9/3                                         7.5GY 5/7  5G 5/8     7.5R 4/11                                         ______________________________________                                     

We claim:
 1. The new and distinct variety of strawberry plant illustrated and described and having the characteristics above enumerated. 